Update release artifacts

[ryannedolan]

Summary

• Added hoptimator-jdbc-driver fat jar artifact.
• Added hoptimator-api artifact.
• Moved Source, Sink, Job, Pipeline, and MaterializedView to hoptimator-api module.
• Added SqlDialect enum.
• Upgraded gradle.
• Fixed non-determinism in tests.

Details

I endeavored to release the fewest number of artifacts while still being useful to downstream projects. For now, I think we can get away with just a driver "fat jar" and the API module. The hoptimator-util module is intended to make extending Hoptimator easier, but it should not be strictly necessary for most use cases.

The hoptimator-api module was missing Source, Sink, etc, which are necessary hooks to extend core functionality. I moved these to hoptimator-api. Otherwise the API wouldn't be particularly useful.

The Source and MaterializedView classes depended on Calcite's RelDataType and SqlDialect. I dropped methods and introduced our own SqlDialect enum to avoid introducing a dependency on Calcite. The API module should always have zero dependencies.

Testing Done

make integration-tests

[ryannedolan]

Thinking more about this, I'm going to change the SqlDialects to match the target engines: FLINK, ANSI for now. In particular, I think it will be nice to have flinksql in templates.

[jogrogan]

LGTM